Constrained Dipeptide Surrogates: 5- and 7-Hydroxy Indolizidin-2-one Amino Acid Synthesis from Iodolactonization of Dehydro-2,8-diamino Azelates

The constrained dipeptide surrogates 5- and 7-hydroxy indolizidin-2-one N-(Boc)amino acids have been synthesized from L-serine as a chiral educt. A linear precursor ∆⁴-unsaturated (2S,8S)-2,8-bis[N-(Boc)amino]azelic acid was prepared in five steps from L-serine. Although epoxidation and dihydroxylation pathways gave mixtures of hydroxy indolizidin-2-one diastereomers, iodolactonization of the ∆⁴-azelate stereoselectively delivered a lactone iodide from which separable (5S)- and (7S)-hydroxy indolizidin-2-one N-(Boc)amino esters were synthesized by sequences featuring intramolecular iodide displacement and lactam formation. X-ray analysis of the (7S)-hydroxy indolizidin-2-one N-(Boc)amino ester indicated that the backbone dihedral angles embedded in the bicyclic ring system resembled those of the central residues of an ideal type II’ β-turn indicating the potential for peptide mimicry.     

促红细胞生成素B螺旋表面肽的代谢稳定性结构修饰：设计、合成及其提高的肾保护作用

肾脏缺血缺氧以及再灌注过程都将导致肾小管上皮细胞凋亡,使肾功能严重受损.肾脏的缺血再灌注损伤是移植肾功能延迟恢复的主要原因并能诱导急慢性排斥,影响肾存活率.近年来发现,衍生于促红细胞生成素（EPO）的B螺旋亚基亲水表面序列的肽链（HBSP）,对肾脏缺血再灌注损伤具有显著的保护作用,但其在体内极短的半衰期（约2min）极大地限制了它的临床应用.因此,本研究采用构象约束、全D-构型氨基酸替换和N-端封闭策略,设计了3种类型的EPOB螺旋表面肽衍生物,旨在提高其代谢稳定性环肽的设计采用了对氧化还原稳定的硫醚键和相对刚性的亚砜键两种环合方式.在多肽的合成上,采用微波辅助多肽自动合成和手工合成两种模式有机结合;优化了硫醚环合工艺,应用微波加热进行硫醚环肽的合成,大大提高了产率和效率;利用圆二色（CD）谱确定了亚砜环肽的相对构型.活性实验表明,相对于线性母肽HBSP,本文设计合成的代谢稳定衍生肽对大/小鼠肾脏缺血再灌注损伤均有显著提高的保护作用,且硫醚和R-构型亚砜环肽的肾脏保护活性强于S-构型亚砜环肽.而且,环化确实提高了功能肽的血浆稳定性.因此,本文合成的硫醚环肽一周一次注射剂量等效于线性肽HBSP一日三次剂量对小鼠肾损伤的保护作用.     

Treatment of Human Glioblastoma U251 Cells with Sulforaphane and a Peptide Nucleic Acid (PNA) Targeting miR-15b-5p: Synergistic Effects on Induction of Apoptosis

Glioblastoma multiforme (GBM) is a lethal malignant tumor accounting for 42% of the tumors of the central nervous system, the median survival being 15 months. At present, no curative treatment is available for GBM and new drugs and therapeutic protocols are urgently needed. In this context, combined therapy appears to be a very interesting approach. The isothiocyanate sulforaphane (SFN) has been previously shown to induce apoptosis and inhibit the growth and invasion of GBM cells. On the other hand, the microRNA miR-15b is involved in invasiveness and proliferation in GBM and its inhibition is associated with the induction of apoptosis. On the basis of these observations, the objective of the present study was to determine whether a combined treatment using SFN and a peptide nucleic acid interfering with miR-15b-5p (PNA-a15b) might be proposed for increasing the pro-apoptotic effects of the single agents. To verify this hypothesis, we have treated GMB U251 cells with SFN alone, PNA-a15b alone or their combination. The cell viability, apoptosis and combination index were, respectively, analyzed by calcein staining, annexin-V and caspase-3/7 assays, and RT-qPCR for genes involved in apoptosis. The efficacy of the PNA-a15b determined the miR-15b-5p content analyzed by RT-qPCR. The results obtained indicate that SFN and PNA-a15b synergistically act in inducing the apoptosis of U251 cells. Therefore, the PNA-a15b might be proposed in a “combo-therapy” associated with SFN. Overall, this study suggests the feasibility of using combined treatments based on PNAs targeting miRNA involved in GBM and nutraceuticals able to stimulate apoptosis.     

猪皮胶原肽-锌螯合物的制备工艺研究

研究猪皮胶原肽-锌螯合物的制备工艺。以猪皮为原料,制备猪皮胶原肽-锌螯合物;以螯合率为指标,研究了猪皮胶原肽与锌质量比、pH、温度、时间对螯合率的影响;通过单因素试验、响应面法试验考察优化猪皮胶原肽的富锌工艺。结果显示,猪皮肽-锌螯合的最佳工艺为猪皮肽与锌质量比2:1,螯合pH 7.0,螯合温度50 ℃,螯合时间50 min,在此条件下,试验螯合率最佳,为69.27%,与模型预测值69.92%相近。该研究为新型生物肽 锌螯合物的研制、猪皮的高值化利用提供了依据。     

Development,validation and application of a UHPLC–MS/MS method for quantification of the adiponectin-derived active peptide ADP355 in rat plasma

A UHPLC–MS/MS method for the quantification of ADP355, an adiponectin-derived active peptide, was developed and validated. The extraction method employed simple protein precipitation using methanol and chromatographic separation was achieved on anAccucore™ RP-MS C₁₈ column (100 × 2.1 mm, 2.6 μm, 80 Å), using 0.1% formic acid in both water and acetonitrile with gradient elution at the flow rate of 400 μl/min within 4.0 min. Detections were performed under positive ion mode with multiple reaction monitoring ion transitions m/z 1109.2 → 309.8 and 871.4 → 310.1 for ADP355 and Jt003 respectively at unit resolution. The linearity range of the calibration curve was 2–1,000 ng/ml with a lower limit detection of 0.5 ng/ml. The selectivity, linearity, precision, accuracy, recovery, matrix effect and stability were validated, and all items met the requirement of US Food and Drug Administration guidance. This method was successfully applied to an intravenous pharmacokinetic study of ADP355 in rats and the in-vitro stability in rat serum, plasma and whole blood was also assessed.     

Chemical analysis of Gothic mortar from a bridge pier in Roudnice nad Labem (Czech Republic)

In this paper, a Gothic mortar originating from the remains of a bridge pier in Roudnice nad Labem (Czech Republic) was analyzed. The inorganic composition of the mortar showing special mechanical properties was studied using polarizing light microscopy, scanning electron microscopy coupled with energy dispersive X-ray spectrometry, and X-ray diffraction, while the protein content was analyzed by peptide mass mapping using matrix-assisted laser desorption/ionization—time of flight mass spectrometry and nanoliquid chromatography coupled to tandem mass spectrometry. Two types of inorganic binders having a composition similar to mineral wollastonite and hydraulic lime and milk protein additive were detected. We believe that organic and inorganic binders added together to the mortar increase its hardness and firmness in the aquatic environment.     

Study of peptide conformation in terms of the ABEEM/MM method

The ABEEM/MM model (atom-bond electronegativity equalization method fused into molecular mechanics) is applied to study of the polypeptide conformations. The Lennard-Jones and torsional parameters were optimized to be consistent with the ABEEM/MM fluctuating charge electrostatic potential. The hydrogen bond was specially treated with an electrostatic fitting function. Molecular dipole moments, dimerization energies, and hydrogen bond lengths of complexes are reasonably achieved by our model, compared to ab initio results. The ABEEM/MM fluctuating charge model reproduces both the peptide conformational energies and structures with satisfactory accuracy with low computer cost. The transferability is tested by applying the parameters of our model to the tetrapeptide of alanine and another four dipeptides. The overall RMS deviations in conformational energies and key dihedral angles for four di- or tetrapeptide, is 0.39 kcal/mol and 7.7 degrees . The current results agree well with those by the accurate ab initio method, and are comparable to those from the best existing force fields. The results make us believe that our fluctuating charge model can obtain more promising results in protein and macromolecular modeling with good accuracy but less computer cost.     

Investigation of the interaction between HⅣ-1 DNA and cyclic peptides by electrospray ionization mass spectrometry

The interaction between HⅣ-1 DNA and five cyclic peptides (CP1-CP5) was investigated using electrospray ionization mass spectrometry (ESI-MS). It revealed that CP1 [c(Ala-Tyr-Leu-Ala-Gly)] and CP4 [c(Pro-D-Tyr-Leu-D-Ala-Gly)] have the higher binding affinity with the duplex DNA among the five cyclic peptides.     

一种基于遗传算法的肽/蛋白质结合模式虚拟筛选建模技术

“合理”QSAR模型是指在了解配体与受体相互作用模式的前提下建立定量构效关系, 这样避开了传统做法仅仅依靠样本集分子自身信息来构建预测模型的诸多弊端. 本文将此思想应用于肽/蛋白质亲和活性的研究当中, 借助于遗传算法作为虚拟受体结合靶点及相互作用模式的筛选手段得到了一种新的建模技术: 肽/蛋白质结合模式遗传虚拟筛选(genetic virtual screening of combinative mode for peptide/protein, GVSC). 该法成功解决了“合理”QSAR研究中的难题, 即大多数情况下受体结构未知而难以了解配基与之发生的结合方式. 分别使用58个血管紧张素转化酶, 18个Camel抗体蛋白cAb-lys3双位点突变残基对GVSC加以检验, 其结果表明GVSC能够较好地阐明配基与受体之间的作用机理, 并能得到优于传统方法的QSAR模型.